Study On The Effect Of Mixed Strains On Wax Removal And Viscosity Reduction Of Crude Oil

As the temperature of waxy crude oil decreases during transportation,the flowability of crude oil decreases,which brings potential safety hazards for pipeline blockage.As a new technology which can effectively solve the problems of waxy crude oil such as high pour point and poor fluidity,biodegradation technology has the advantages of safety,environmental protection,low cost and high economic benefit compared with the traditional high-cost and high-energy-consuming technologies such as heating transportation,additive transportation and dilute transportation.Based on the mechanism of microbial wax removal and viscosity reduction,a series of experiments were carried out,mainly in the following aspects:Firstly,preparation of wax removal bacteria.Four strains of bacteria and one strain of surfactant-producing bacteria were isolated from the soil contaminated by waxy crude oil in Daqing.By 16 SrDNA identification,four strains of waxy-removing bacteria were identified as Gordonella,Microbacterium,Xanthomonas and Achromobacter and surfactant-producing bacteria were Pseudomonas.The four dewaxing bacteria were mixed with surfactant-producing bacteria in different proportions,and the optimum proportions were 1:1,2:3,1:1 and 3:2.Secondly,the growth environment and metabolite analysis of the strain were optimized.The optimum growth environment of four mixed strains was optimized with initial culture temperature,pH value and salinity as variables.The four mixed strains could produce lipopeptide metabolites,and had good surface tension reduction and oil expulsion activity.Finally,the effect of mixed strains on wax removal and viscosity reduction of waxy crude oil was analyzed.The wax content,wax precipitation point and wax precipitation peak point of waxy crude oil before and after treatment by mixed bacteria were detected.It was found that mixed bacteria could reduce wax precipitation point of waxy crude oil by 2.11?,wax precipitation peak point by 1.5? and wax content by 39%.The wax crystal morphology of waxy crude oil before and after treatment by mixed bacteria was observed.The apparent viscosity of waxy crude oil before and after treatment with mixed bacteria was measured by rheometer,and it was found that the apparent viscosity of crude oil could be reduced by 19.8%.The experimental results show that the mixed strains can effectively reduce the wax content and apparent viscosity of crude oil,and effectively improve the fluidity of crude oil.